Apparatus for electric arc stud welding



y 6, 1953 A. R. AINSWORTH ETAL 2,640,133

APPARATUS FOR ELECTRIC ARC STUD WELDING 1 2 Sheets-Sheet 1 Filed March27, 1950 Wh Om y 25, 1953 A. R. AINSWORTH ET AL APPARATUS FOR ELECTRICARC STUD WELDING 2 Sheets-Sheet 2 Filed March 27, 1950 a up aw 3 t. Nu Now @h an QM. hm Q Om N.

mm mm mwww mmdw N6 hm a MN a F SN Q R Q Patented May 26, 1953 APPARATUSFOR ELECTRIC ARC STUD WELDING Arthur Ratcliife Ainsworth and JamesBinnie Miller, London, England, assignors to Cyc-Arc Limited, London,England, a British company Application March 2'7, 1950, Serial No.152,136 In Great Britain April 6, 1949 12 Claims.

This invention relates to apparatus for the electric arc welding ofmetal or alloy studs, tubes, rivets, rods and the like (hereinaftertermed studs) to metal or alloy plates, strips, bodies or the like(hereinafter termed plates). The apparatus is of the type in which thestud chuck, after being charged with a stud, is moved relatively to thebody of the apparatus against an opposing force on the butting oi thestud upon the plate to which it is to be welded as the apparatus is setin a determined position in relation to the plate, the apparatus beingprovided with operating means whereby the stud chuck carrier may beretracted by force through a limited distance from the plate for thestriking of an are between the stud and the plate. While it is essentialto determine precisely the extent of the said limited distance, it isdesirable that the disposition of the stud chuck carrier in relation tothe body of the apparatus after the butting of the stud upon the plateshall be variable over a considerable range, in order that differinglengths of studs may be welded in succession without necessity foradjustment of any of the elements of the apparatus.

The invention has among its objects to facilitate the welding of studsof difiering lengths without the preliminary adjustment of any of theelements of the apparatus, to provide simple and effective means toretain the stud chuck carrier in any adjusted position inrelation to thebody of the apparatus, to provide means whereby the distance between thestud and the plate for the striking of the arc may be determinedirrespective of the relative disposition of the stud chuck carrier andthe body of the apparatus, to provide a light weight portable or handtool that may be manufactured at a low cost and generally to provide animproved apparatus that may be small and comp-act in form while having aconsiderable working capacity.

According to the invention the apparatus comprises a stud chuck carrierhaving a wide range of movement in relation to the body and consistingof at least two parts that are coupled together in a manner to permitrelative movement of the parts to a degree represented by the determinedlength of the are between the stud and the plate at striking and so thatthe parts always tend to take up the disposition in which such relativemovement is possible and electromagnetically operating means foreffecting the frictional engagement and retention of the stud chuckcarrier in any position in relation to the body into which it may havebeen moved by the butting of the stud upon the plate when the apparatusis set in the operative position in relation to the plate.

In an apparatus in which the retraction of the stud chuck carrier forthe striking of the arc is effected by the movement of a solenoid coreon energisation of the solenoid, the stud chuck carrier convenientlycomprises the said core and a clutch member or members couplied to thesaid core in the required manner and adapted to be subjected to thefrictional restraint necessary to arrest the stud chuck carrier in theposition which it has taken up on the setting of the apparatus in theoperative position. The clutch member or members and th solenoid corethus form the coupled parts of the stud chuck carrier.

The frictional restraint may be imposed by providing in the body of theapparatus a clutch surface inclined to the surface of the co-actingclutch member, so that a space of wedge-like cross-section is formedbetween the two surfaces, and by interposing between the two surfaces aclutch element that is maintained out of contact with the surfaces byspring action and is moved into contact by pressure app-lied from thearmature or core of the electro-magnetic oper ating means. In anotherform, the clutch memher or members may be attracted magnetically intocontact with a surface or surfaces lying parallel with the axis oftravel of the stud chuck carrier on the energisation of theelectro-magnetic operating means.

The function of retracting the stud chuck car rier and the function ofimposing the frictional restraint may be performed by the sameelectromagnetic means or by distinct electro-magnetic means.

The coupling of the parts or" the stud chuck carrier is advantageouslysuch that the extent of the movement of retraction of the stud chuck forthe striking of the arc may be varied or adjusted.

Th invention further comprises the features hereinafter described andclaimed.

The invention is illustrated, by way of example, in the accompanyingdrawings of two constructions of portable or hand welding tool.

Figure l is a longitudinal section of a construction of tool accordingto the invention.

Figure 2 is a front elevation of the tool represented in Figure 1.

Figure 3 is a longitudinal section of a modified construction of handtool according to the invention.

Figure 4 is a front elevation of the tool represented in Figure 3.

In carrying the invention into eiifect in the construction of a portableor hand tool provided with an arc-striking solenoid, as illustrated inFigures 1 and .2 of the accompanying drawings, a steel or like tubularcasing or body 1 has an annular abutment member 5: secured within it ata distance from the forward end. The spool or former 3 of the solenoidcoil 1 is fitted to the rear of the abutment mer' er 2 and is followedby an inner lining member of steel or other magnetic material, having atthe forward end a massive flange 6 that rests upon the former 3 andclosely fits the wall of the body 5. The lining member 5 is of a form topresent between it and the wall of the bod I an annular space in whichis positioned the former 2', of insulating material, of a clutch coil 3.The former i is secured in position by a retaining rin 9- which closelyfits about the rear end oi the lining member 5, and a lock ing ring it,each peripherally screw-threaded to engage an internal screwthreadformed in the end of the wall of the body I. The ring 10 is ofmagnetic material and forms a pole piece.

The lining member 5 has the bore formed in steps of three diameters,that of the smallest diameter, ii, having a diameter that is somewhatsmaller than the diameter of the bores of the former 3 and of theabutment member 2. The second step, it, is of a diameter to afford anannular space for the reception of a helical spring E3. The third step,ii, of the largest diameter, is adapted to receive upon the shoulderformed at the change of diameter a cone ring 15, of hardened steel.

The forward end of the body 1 is closed by a closure ring havin a boreof a diameter to receive the stud chuck carrier with a sliding fit andadvantag ously provided with a stuffing box and gland. to retain packingabout the stud chuck carrier.

The stud chuck carrier consists in the main of the solenoid core l? andthe clutch member I8. The solenoid core is a cylindrical body ofmagnetic material that may be, for the greater part of its length, solidbut is advantageously bored or recessed except for the rear end, forreduction of weight. The forward part of the core is of a diameter toslide through the closure ring and its stuffing box, while the remainderis of a diameter to slide within the abutment member 2 and the former 3.A piston 19 is fitted to the core I'i at the shoulder formed by thechange of diameter and is secured in position, for example, by a cottern. A piston ring 23 ensures an air-tight fit with the wall of the body Iwhile the boss of the piston determines the outer limit of travel of thecore from the body I and also en-- sures the presence or" a residual airspace or cushion'between the piston and the closure ring it. A helicalspring 2! is confined between the piston and the abutment member 2 andthus provides the biassing force tending always to move the solenoidcore to the outer limit of its travel. The core is convenientlyprevented from rotating by means of a constraining pin 22 fittedin theboss or flange of the abutment member 2 and engaging a longitudi .i slotor key-way in the core.

The clutch "m mber 18 is a cylindrical body of magnetic material that isa sliding fit within the step H of the smallest diameter of the bore ofthe lining member a and therefore is separated from the bore of theformer 3 by an annular air space. It passes freely through the spring l3and, in the neighbourhood of the cone ring l5,

slidably through an abutment ring 23, of nonmagnetic material, and intothe tubular armature 24 of the clutch coil 8. The armature 24 is ofmagnetic material and is a clearance fit within the step I4 of the boreof the lining member 5. At the rear end it is peripherally screwthreadedto receive an annular pole piece 25 and a lock nut 23. The pole piece 25is adapted to co-act with the pole piece formed by the ring l0. Betweenthe forward end of the armature 24 and the abutment ring 23 there arepositioned several steel or like balls 21.

The clutch member is bored from the rear end for the greater part of itslength, in two sections of differing diameter, the larger diameter beingto the rear. At the change of diameter there is formed a screw thread toreceive a screwed plug 28 which serves as an abutment for a helicalspring 22 which, at the forward end, bears upon a collar 36 formed upona coupling screw 3i that passes freely through a bore of small diameterin the forward end of the clutch member and has the forward partscrew-threaded to engage a screw-threaded bore in the rear end of thecore 17, and also, if required, a, lock nut 32. The coupling screw 3| isof non-magnetic material. By adjustment of the screw in the core ll, itis possible to ensure that, under the pressure of the spring 29, thecore is normally separated from the clutch member l8 by a distancerepresenting the required lift or spacing of the stud from the plate towhich it is to be welded for the striking of the arc.

The part of the core I! that extends from the closure ring it is boredto receive the stem 33 of an insulator having a disc head 34 and whichis itself bored to receive a screwed pin 35. A brass or like conductingdisc 36 faces the head 34 and is pinned thereto. The insulator stem 33is secured in the core I! by screw thread engagement or by a pin 31. Aneyelet 38 provided at the end of the welding cable 39 is secured inposition upon the pin 35 between the disc 36 and a nut 46. The studchuck 41 is received upon the end of the pin 35.

The rear end of the body I is closed by a cap 42 to which is secured thehandle 43 provided with the press switch 44. The cap 42 may convenientlycarry an adjustable stop pin 45 by which the air gap between the polepieces I 0 and 25 when not attracted may be determined.

The body I is advantageously fitted with a stout sheet metal cylindricaltool support 46 that is a sliding fit upon the body and, for the forwardpart, is cut away in diametrically opposite positions, as at 41' and 43,in the one case, to permit the ready fitting of studs in the stud chuck4| and, in the other case, to permit the welding cable 39 to beconnected to the stud chuck carrier. The forward end of the tool support46 is fitted with an interrupted ring 49 supporting three equally spacedpins 50 whereby the apparatus may be set upon the plate in the operativeposition for the welding of the studs. The pins may be adjustable forlength of protrusion from the ring 49. The latter conveniently serves tocarry a short tubular ferrule clip or support 5|, that is flangedoutwardly at the lower end to form a seating for the ferrules 52 and asan abutment for a helical spring 53 positioned between the flange andthe ring 49. The upper end of the clip or support Si is also flangedoutwardly or provided with a retaining nut, to prevent withdrawal of theclip from the ring 49. The lower end of the clip is split or slotted toafford resilience.

In order that the tool support 46'may bead- J'usted in position upon thebody I, the upper or rear end 54 is split and the two ends provided withlugs 55 for the reception of a clamping screw 56.

In operation, when the stud chuck H is charged with a stud and theapparatus is set so as to be supported by the pins 55 upon the plate towhich the stud is to be welded, the contacting of the stud with theplate moves the stud chuck carrier freely into the body of the toolagainst the force of the spring 2|, the core l1 and the clutch member l8maintaining their spaced relation under the pressure of the spring 29upon the collar 30. When the switch 44 is closed to initiate the weldingoperation, the clutch coil 8 and the solenoid coil 4 are energised. Thearmature 24', is thus attracted to reduce or close the air gap betweenthe pole pieces Ill and 25 and presses the balls forwardly along thecone ring [5, so that they are caused to grip and immobilise the clutchmember it. The energisation of the solenoid coil 4 results in theretraction of the core I! to the extent permitted by the gap between thecore and the clutch member, thus moving the stud from the plate to thedetermined distance required for the striking of the arc. On theexpiration of the determined duration of the arc, the control circuitsare opened and the coil 8 and. solenoid 4 deenergised. The spring [3 isthus permitted to move the balls 2'! and the armature 24 rearwardly, 31

so that the clutch member is released, and the stud chuck carrier ismoved forwardly by the spring 2| to carry the heated end of the studinto contact with the heated crater of the plate at a speed that may bedetermined by the dampening effect of the piston IS. The damping eifectmay be dependent upon the presence of a bleed hole or valve whereby thepassage of air into and from the space between the piston and theclosure ring It may be controlled.

If the clutch coil 8 and the solenoid coil 4 are included in the samecontrol circuit, it is advisable to ensure that the former is energisedmore rapidly than the latter. For example, sufficient retardation in theoperation of the solenoid coil 4 may be secured by forming the coilformer 3 of a conductive metal or alloy, such as brass, so that eddycurrents may be induced therein for the purpose of momentarily retardingthe operation of the solenoid. The solenoid coil may alternatively beincluded in a control circuit that is dependent for its closure upon thepassage of current in the control circuit containing the clutch coil 8.

It is advantageous, but not essential, to provide the solenoid core andthe clutch member of circular cross-section. If they are non-circular,the cone ring or tapering bore may be replaced by a series of planeinclined surfaces that may cooperate with wedges, segmental blocks orrollers as the clutch elements. If the clutch member is adapted to slidein a guide or guides, a single inclined surface and a single clutchelement may suflice to impose the required restraint upon the clutchmember.

Figures 3 and 4 illustrate a simplified construction of portable or handtool in which a single coil functions as the clutch coil and thesolenoid coil and in which a diifering form of electromagneticfrictional restraint is imposed upon the stud chuck carrier. Since,however, much of the construction is similar in detail to that of thetool represented in Figures 1 and '2, the distinguishing features onlywill be described in detail and like parts will be indicated by the samereference numerals.

The body 51 is closed at th forward end by the closure ring I6 and atthe rear end by the massive flange 58 of the former 59, of magneticmaterial, of the coil 60. The forward flange 6| of the former 59 takesthe place of the abutment member 2 and is formed accordingly as anabutment for the spring 2|. The diameter of the bore is such as topermit the core I! to move therein, but the forward part is recessed forthe reception of a lining 62 of non-magnetic material, so that the coredoes not adhere. The rear part of thebore is roughened or scored,preferentially circumferentially, as at B3.

The core I1 is provided with a solid extension 64 that remains alwayswithin the bore of the former 59 and is fitted with a sleeve 65 and, ifrequired, a washer 66, or a cap, of non-magnetic material. The saidsolid extension 64 is bored axially and tapped to receive a headed screwor bolt 61 that functions as the coupling element between the core andthe clutch member. The latter is a cylindrical body 68 of magneticmaterial fitting closely within the roughened surface 63 of the bore ofthe former 59 and divided into two parts of substantially semi-circularcrosssection. The two-part body is bored to be a sliding fit upon thescrew or bolt 61 and the forward face is recessed at 69 to form anannular space about the screw or bolt 61, in which space is disposed ahelical spring 10 confined between the washer 6B, or cap, of theextension 64 and the rear end of the body 68. A washer H, ofnon-magnetic material, is advantageously disposed under the head of thescrew or bolt 61. The spacing of the body 68 from the core I"! under thepressure of the spring 10 represents the lift of the stud from the platefor the striking of the arc. The distance may be readily adjusted byadjustment of the screw or bolt 61 in the end of the core IT. Theperipheral surface of the two-part body 68 is roughened in a mannersimilar to the roughening of the bore of the former 59.

Figure 3 illustrates the provision on the closing ring [6 of anon-return ball or other spring valve 72 for the admission of air to thespace between the closing ring and the piston [9, to facilitate theinward movement of the stud chuck carrier and to effect a dampening ofthe return movement of the stud to the plate, to avoid impact of thestud upon the plate.

The handle 13 is secured to the rear end of the body 5'! and to theflange 58 of the former 59. It is fitted with the switch 44, which maybe of any required type, and receives the welding circuit cable 39, aswell as the cable of the control circuit. The cable 39 passes from alateral boss of the handle to the eyelet 38.

In operation, when the coil 60 is energised, the parts of the clutchmember 68 are instantly attracted by the former 59 and move intoengagement therewith, thus immobilising the stud chuck carrier. At thesame time the core 11 is caused to move rearwardly to the extentpermitted to it and thus lifts the stud from contact with the plate.

It is not essential for the former 59 to be wholly of magnetic material.The magnetic material may form a lining to the former, either wholly orin par-t. The clutch member, also, may be provided in more than twoparts, so long as the said parts, or certain Of them, have a limitedfreedom of lateral movement in relation to the coupling element topermit of the attraction into contact with the surface of the coilformer. Such parts may be mounted in a carrier.

The invention is not limited'torthe'features of Thus, in

by -metalwashers disposed at theitwo sides and aretaininganut upon theforward. endof the pistonwrod.

ine outer .end of the piston. rod-may be closed by a plug-or by.an'adjustable valve affording a controlled entry for air.

.It willalw betunderstood that the means for r restraint comprisingclutch elements may be'used with a single operating coil, providing thatthe required sequence of operation ofthe clutch members and elements andof the solenoid coil is maintained. Similarly,the

magnetic type of clutch membermayrbe used in connection with anoperating coil distinctifrom ,thesolenoid.

We claim:

vlaElectric arc weldingapparatusfor welding Q studsto plates,comprising-a body, a stud chuck .carrier axially movable :in the bodyandconsisting of two co-axial relatively movable parts,

a couplingmember connecting the two parts and determiningthe maximumdistance of their posno .sibleseparationand yieldablemeans acting toseparatethe parts to such maximum distance, clutchmeans within the bodyand operable to eifect clutching engagement with the inner part of thestud chuck carrier: to immobilize the said inneripart andelectromagnetic-means for attracting theouter'part'into contact with theinner part.

2.'Electric arcwelding apparatus for welding studsto plates, comprisingabody, astud chuck carrier. axially movable in the'body andconsisting-of-two=.co-axia1 relatively movable parts, a coupling memberconnecting the parts and determining the maximum distance of separationof the. two partsand yieldable meansacting'to separatethe parts to suchmaximum distance, clutch means within the body operable to clutch andimmobilize the inner part of the studchuck carrier in anyposition intowhich it. is moved when the apparatus is set in the operative positionin relation-totheplate to which a stud carried in the chuck is to bewelded-and the stud butts upon the-Plate, andxmeans in the' body formoving the outer part of the-stud chuckcarrier into .con-

tact with the inner. part.

3. Electric arc Welding apparatus for welding studs to plates,comprising a bodyyacstud chuck carrieiwmounted in thebody formovementlinthe directionof the axis of thechuckandconsisting of inner and outerco-axial parts, a coupling member connecting the two parts'withilimitedfreedom of relative axial movementand yieldable means actingon andforcing the'two partsto the maximum distance of separation, whichdistance represents the length'at striking of the arcto bestruckbetweenthe stud inthe chuck and the plate to which the stud is tobe welded, yieldable means-forcing the stud chuck carrier outwardly fromthe body, clutch means positioned inthebody and operable-to'clutch andimmobilize the inner part of the stud chuck carrier and electro-magneticmeans in, the body foroperating the clutch-means andattracting the outerpart of the studchuck carrier into contact with the inner part.

4.Electric arcrweldingapparatus for welding .studs to plates, comprisinga body, astud chuck .carrieraxially movable inthe'bodyand consisting ofinner and outer co-axial parts, a coupling member connectingithe two.parts and afiording thereto limited freedom of relative axialmovementand yieldable means tending always to separate the parts .tothemaximum distance apart, clutch means within the body adapted toclutch and immobilize the inner part of the stud chuck carrier in anypredetermined positionin relationto the body and a solenoid within thebody, which-solenoid, when energised, attracts, as

a core, the outer part of the stud chuck carrier into contact with theinner part.

5. Electric arc welding apparatus for welding studs to plates,comprising a body, astud chuck carrier axially movable in the body andconsisting of inner and outer co-axial parts, an adjustable couplingmember connecting the two parts with limited but regulatable freedom ofrelative axial-movementand yieldable means tending always to separatethe parts to the maximum distance apart, clutch means in the bodyadapted to immobilize the inner part in any predetermined position inrelation to the body and electro-magnetic means for operating the clutchmeans and for moving the outer part of the stud chuck carrier to itsinner limit of movement relatively to the inner part.

6. Electric arc welding apparatus for welding studs to plates,comprising a body, a stud chuck carrier axially inovable-in the body andconsisting of an inner clutch part and an outer core part, a couplingelement connecting the two parts with limited freedom of relative axialmovement and yieldable means tending-always to dispose the parts at themaximum distance apart, which distance represents the length at strikingof an arc to be struck between stud in the chuck and the plate to whichthe stud isto be welded, yieldable means tending always to move the studchuck carrier outwardly from the body, clutch 'means within the bodyadapted to immobilize the clutch part'in anyposition into which it ismoved when the apparatus is set in the operative position in relation tothe plate to which the stud in the .chuck'is to be welded and the studbutts upon the plate and electro-magnetic means comprising at least onecoil in the body surrounding the pathof movement of the stud chuckcarrierand serving, when energised, to operate the clutch means and tomove theouter core part to its inner limit of movement relatively to theinner part.

7. Electric arc Welding apparatu for welding studs. to plates accordingto claim 6, in which the electro-magneticomeans comprise a clutch coilanda solenoid, which, when energised, respectively eff ect. theoperation of the clutch means and movethe outer core part to the innerlimit of its travel relatively to theinnerpart, the coiland solenoidbeing co-axially disposed.

8. Electric arc welding apparatusfor welding studs to plates accordingtoclaimfi, in whichthe electroemagnetic means comprise asolenoid coil,which, vhen energisedeifects the operation of the clutch means and movesthe outer. core part to the inner limit of its movement relativelytorthe inner part.

9. Electric arc welding apparatus for welding studs to plates,accordingto claim 6, in which the clutchjmeans for co-operation with theinner clutch part ofthe stud chuck carrier comprise at least one surfacein the body inclined to theinurface of the said part, a clutch elementdisposed between the two surfaces, 2, spring acting upon the clutchelement to throw it out of contact with the two surfaces and an armaturein a position in relation to the clutch element opposed to the springand moving to press the clutch element into engagement with the twovsurfaces against the action of the spring, on energisation of theelectro-magnetic means.

10. Electric arc welding apparatus for welding studs to plates,according to claim 6, in which the clutch means comprise an annularconed surface within the body and surrounding the inner clutch part ofthe stud chuck carrier, a series of clutch elements disposed between theconed surface and the surface of the said inner part, a springpressedabutment element upon which the clutch elements rest out of contact withthe two surfaces and an annular armature disposed in an opposed positionwith reference to the abutment element and pressing the clutch elementsinto contact with the two surfaces, on energisation of theelectro-magnetic means. I

11. Electric arc welding apparatus for welding studs to plates,according to claim 6, in which the clutch means comprise a magneticcontact surface in the body, which, on energisation of theelectro-magnetic means, becomes active to attract the inner clutch partof the stud chuck carrier into contact therewith, by limited movementtransverse to the axis.

12. Electric arc welding apparatus for welding studs to plates,according to claim 6, in which the clutch means comprise a magneticcontact surface in the body surrounding the inner part of the stud chuckcarrier and that the said inner part comprises at least two sectionsthat are divided one from another on planes radial to the axis of thepart and that are adapted for separation in directions transverse to thesaid axis, for attraction into contact with the contact surface of thebody, which becomes active to efiect such attraction on energisation ofthe electro-magnetic means.

ARTHUR RATCLIFFE AINSWORTH. JAMES BINNIE MILLER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,265,169 Hughes et a1 Dec, 9, 1941 2,467,723 Barlow Apr. 19,1949 FOREIGN PATENTS Number Country Date 584,695 Great Britain Jan. 21,1947 592,084 Great Britain Sept. 8, 1947 601,567 Great Britain May 7,1948 619.962 Great Britain Mar. 17, 1949

